measurements, methods and instrumentation
Domján, Á. (1)
(1) MinGeo Ltd., Budapest, Hungary
Absolute geomagnetic measurement is an
accurate determination of magnetic declination D and inclination I at
a given location and time on the Earth. These quantities are essential
to monitor the long-term baseline changes and calibration parameters
of variometers in observatories and repeat station surveys.
Methods and the instrumentation are tightly coupled to this kind of
measurement. Since all the relevant methods based on the usage of a
classical theodolite equipped with flux-gate magnetometer known as
declination inclination magnetometer (DIM). The most commonly used
method in the magnetic community is the null method. In the null
method procedure we need to find the close to zero magnetic output of
the magnetometer in a predefined sequence. Then the processing is not
more than additions subtraction and mean calculation.
In the article of (Brunke and Matzka, Numerical evaluation of magnetic
absolute measurements with arbitrarily distributed DI-fluxgate
theodolite orientations, 2018) a new method was proposed, where the
determination of D and I is a search for global minimum of the
non-linear inverse problem of the DIM instrument model. This method
more general than null method. There is no rigorous constrain about
the measurement protocol and it can process the null method data too.
DIMs have several difficulties. Measurement procedure is carried out
manually. Difficult to use DIM for I observation in equatorial region
because the telescope cannot be read in nearly vertical position even
with diagonal eyepiece. The computation of magnetic meridian is
calculated by the operator during the measurements.
To overcome this problem at MinGeo company we developed a cable-less,
digital, non-magnetic DIM instrument, known as the FluxSet Declination
Inclination Digital Station 1 (DS-1), which was designed to facilitate
the absolute magnetic measurements.
The aim of this presentation to asses the accuracy and precision of
the absolute magnetic measurements, which were measured by a reference
DIM and DS-1 instrument using null and this new proposed